Cold forcing method and apparatus for producing a terminal

ABSTRACT

A cold forging method and apparatus for producing a terminal comprising the steps of: A first process for feeding a cylindrical blank material into a swaging die and swaging said cylindrical blank material with a first punch to form an enlarged head portion having a shallow recess and a center projection respectively above and below a middle portion maintaining the original outer diameter of the blank material; a second process for feeding an intermediate product obtained in the first process into a pre-pressing die and deeply driving a second punch into the center of said recess in said enlarged head to extrude the material backward increasing its axial length thereby to form a deep center hole which substantially corresponds in diameter with the outer diameter of said second punch; and a third process for feeding an intermediate product obtained in the second process into a forming die except the head and striking it with a third punch comprising a center, a tubular and an outer punch, said center punch being inserted into the center hole of the intermediate product to hold the inner peripheral shape thereof, said tubular punch striking an upper surface of the head, to form, in cooperation with an inner periphery of the outer punch, a flange between the outer punch and a corresponding contact surface of the forming die and a plurality of detent projections on the bottom surface of the flange. In the cold forging method according to the present invention, the terminal can be manufactured with the same accuracy as that of the cut products in the prior art without causing any waste of the material and the production cost can be reduced remarkably.

United States Patent [1 1 Sugahara et al.

[451 Sept. 18, 1973 COLD FORCING METHOD AND APPARATUS FOR PRODUCING ATERMINAL [75] Inventors: Norio Sugallara, Oogaki-City; Tomiji Oguri,Seto-City, both of Japan [73] Assignee: Kabushiki Kaisha Tokai RikaDenki Seisakusho, Aichi Pref., Japan 221 Filed: June 12, 1972 21 Appl.No.: 261,771

[30] Foreign Application Priority Data June 14, 1971 Japan 46/42410 [52]U.S. Cl. 72/356, 72/404, 10/86 F [51] Int. Cl B211: 21/00 [58] Field ofSearch 72/356, 358, 359,

72/377, 404; 10/86 F; 339/217, 220; 113/119; 29/630 R, 630 D PrimaryExaminer-Richard J. l-lerbst Attorney-Woodhams, Blanchard & Flynn [57]ABSTRACT A cold forging method and apparatus for producing a terminalcomprising the steps of:

A first process for feeding a cylindrical blank material into a swagingdie and swaging said cylindrical blank material with a first punch toform an enlarged head portion having a shallow recess and a centerprojection respectively above and below a middle portion maintaining theoriginal outer diameter of the blank material; a second process forfeeding an intermediate product obtained in the first process into apre-pressing die and deeply driving a second punch into the center ofsaid recess in said enlarged head to extrude the material backwardincreasing its axial length thereby to form a deep center hole whichsubstantially corresponds in diameter with the outer diameter of saidsecond punch; and a third process for feeding an intermediate productobtained in the second process into a forming die except the head andstriking it with a third punch comprising a center, a tubular and anouter punch, said center punch being inserted into the center hole ofthe intermediate product to hold the inner peripheral shape thereof,said tubular punch striking an upper surface of the head, to form, incooperation with an inner periphery of the outer punch, a flange betweenthe outer punch and a corresponding contact surface of the forming dieand a plurality of detent projections on the bottom surface of theflange.

1n the cold forging method according to the present invention, theterminal can be manufactured with the same accuracy as that of the cutproducts in the prior art without causing any waste of the material andthe production cost can be reduced remarkably.

2 Claims, 6 Drawing Figures Patented Sept. 18, 1973 2 Sheets-Sheet lPatented Sept. 18, 1973 3,759,080

2 Sheets-Sheet 2 COLD FORCING METHOD AND APPARATUS FOR PRODUCING ATERMINAL The present invention relates to a cold forging method forproducing a terminal adapted to be inserted into casings or insulatingboards of microswitches or other switch devices of synthetic resin andthe like from a cylindrical material without causing waste of material.The present invention aims to efficiently manufacture by forging aterminal of the type as described of the same high accuracy as those cutproducts in the prior art.

The present invention will now be described with reference to theaccompanying drawings.

In the drawings:

FIGS. 1 through 4 are vertical sectional front views showing forgingsequences from a blank material to a final product;

FIG. 5 is an inverted view of the finished product; and

FIG. 6 is a longitudinal sectional view of a forging apparatus.

As shown in FIGS. 4 and 5, a terminal formed in accordance with themethod of the present invention is provided with a flange b above acolumnar middle portion a, and a plurality of detent projections c on alower surface of the flange, which projections taper and connects anouter circumference of the middle portion a with an outer circumferenceof the flange b. Extending from the flange b to the top end, there is ahead d which has the same or slightly larger diameter than that of themiddle portion a. A deep blind bore e starting from the top surface ofthe head d to reach an approximately intermediate point of the middleportion a, and internally threaded at h is formed inside the terminal.There is also integrally formed, at the center of the bottom surface ofthe middle portion a, a projection f of a reduced diameter, which is tobe used as a rivet for caulking a washer inside a switch or an electrodeplate or the like, and a bore g into which a caulking element is to beinserted is formed at an extreme end of the projection f. The thread Itis adapted to threadedly receive a threaded plug k. The entire lengthextending from the lower surface of te middle portion a to the top ofthe head d is inserted into a synthetic resin member I, upon formationthereof, to provide an anti-drawing action by means of the flange b anda detent action by means of the detent projection c.

In this specification the term swaging means a forging process in whicha material is striken to shorten its axial length while increasing itsdiametrical size.

The terminal as shown in FIGS. 4 and 5 is manufactured from acylindrical blank material 1 shown in FIG. I through intermediateproducts as shown in FIGS. 2 and 3. Therefore, the present inventionwill now be described referring to those figures as well as FIG. 6.

The cylindrical blank material 1 shown in FIG. 1 has been preliminarilycut so that each piece has substantially uniform weight, then polishedand annealed to regulate the hardness and then pickled and lubricated.

Forming of an intermediate product 2 as shown in FIG. 2 from thecylindrical blank material 1 is carried out through a first processusing a swaging press machine A of FIG. 6. A swaging die 21 of themachine A has a die hole 22 having a diameter substantiallycorresponding with the outer diameter of the blank material. A hole 23of a reduced diameter, into which an ejector 26 is inserted isconnectingly formed below said die hole 22. Above the hole 22 is formeda hole of an enlarged diameter 25through a short tapered portion 24. Afirst punch 27 substantially corresponding with the hole 25 in diameterhas a small projection 28 centrally provided thereunder. That portion ofthe blank material fed and inserted into the hole 22 which is located inthe enlarged hole 25 is swaged by a strike of the first punch 27 to forma tapered portion 4 and an enlarged head 5 together above the middleportion 3 remaining in the hole 22 and still maintaining the originalouter diameter of the blank material. A center projection 6 is formedunder the bottom of the portion 3 by extrusion into the hole 23 of thereduced diameter and a shallow recess 7 is formed at the center of theupper surface of the head 5 by a strike of the small projection 28 ofthe punch.

Forming of an intermediate product 8 as shown in FIG. 3 from theintermediate product 2 of FIG. 2 is carried out through a second processusing a pre-pressing forging machine B shown in FIG. 6. A pre-pressingdie 29 of the machine B is provided with a die hole 30 of a diametersubstantially corresponding with the outer diameter of the portion 3,that is the outer diameter of the blank material and an axial lengthslightly longer than that of the portion 3, and a die hole 32 of an enlarged diameter substantially corresponding with the outer diameter ofthe enlarged head 5, through a tapered portion 31. Centrally below thedie hole 30 is a hole 33 of a reduced diameter in which an ejector 34 isinserted with its upper surface disposed slightly below the upper faceof the reduced hole 33. A second punch 35 is substantially the same indiameter as the shallow recess 7 and longer than that in axial length.

Now in FIG. 2, the portion 3 of the intermediate product 2 maintainingthe original outer diameter of the blank material is fed and insertedinto the die hole 30 so that the taper 4 engages with the taperedportion 31, and the second punch 35 is driven deeply into the center ofthe recessed hole 7. Thus, by means of the punch 35 driven as deep ashalf of the total length of the portion 3, the center projection 6 isextruded increasingly until it reaches the upper surface of the ejector34 to form a shaft 6a. At the same time, the upper half of the portion3, the tapered portion 4 and the en larged head 5 are extruded behindthe second punch and extended in length respectively to form an extendedmiddle portion 3a still maintaining the original outer diameter of theblank material, an extended tapered portion 4a and an extended enlargedhead 5a as well as a deep center bore 7a having a diameter substantiallycorresponding with the outer diameter of the second punch 35.

Forming of the flnal productas shown in FIGS. 4 and 5 from theintermediate product 8 of FIG. 3 is carried out through a third processusing a finalforging press machine C shown in FIG. 6. In a forming die36 of the machine C is formed a die hole 37 whose length issubstantially equal to the length from the bottom of the middle portiona of the intended product to the lower end of the flange b and whosediameter is substantially equal to the inner diameter of the die hole30. Connected to said die hole 37 is formed a flange forming die hole 38of enlarged diameter which opens in the upper surface of the die 36. Inthe bottom of the die hole 38 are equiangularly formed slanting grooves39 for forming detent ribs C and below the die hole 37 and connectedthereto is formed a hole 40 which is substantially equal in diameter tothe hole 33 of reduced diameter and receives an ejector 41 with itsupper surface disposed slightly below the upper end of the hole 40. Atthe top of the ejector 41 there is projectingly formed a cone 42. Athird punch 43 comprises three parts, that is, a center punch 44 havingthe same diameter as that of the second punch 35, a tubular stripper 45slidably fitted around the outer periphery of the center punch 44 andbiased by a spring 46, and an outer punch 47 encircling the outerperiphery of the stripper 45. The inner diameter of the outer punch 47is made to correspond with the outer diameter of the head d of theproduct shown in FIG. 4.

Now in FIG. 3, the extended portion 3a of the intermediate product 8maintaining the original outer diameter of the blank material is fed andinserted into the die hole 37 of the forming die 36 so that the extendedtapered portion 4a engages with a shoulder 37a at the upper end of saidhole 37, and the extended enlarged head 5a protrudes above the uppersurface of the die 36. The third punch 43 descends to start the formingoperation. When the center punch 44 reaches near the bottom of theCenter bore 7a to sustain the inner face thereof so as not to be changedin diameter the stripper 45 compresses the spring 46 upward through anabutment 48, which in turn abuts against an abutment 49 of the outerpunch 47 as shown in FIG. 6 thereby to press the upper surface of thehead 50. Coincidently, the outer punch 47 presses its lower surfaceagainst the upper surface of the forming die 36 to block the flangeforming die hole 38. By the entrance of the center punch 44 into thecenter hole 7a and pressing of the stripper 45 against the uppersurface, the entire inter mediate product 8 is pressed and a part of theextended tapered portion 4a is urged into the slanting grooves 39 toform equiangularly spaced detent projections 0, while the remaining partof the tapered portion 4a is squeezed by the shoulder 37a to reduce itsdiameter and connect with the columnar portion a of the final productwhich is formed from the extended portion 30 having the original outerdiameter of the blank material. The lower surface of the shaft 60pressed down into the ejector containing hole 40 is correlativelypressed by the cone 42 of the ejector 41 to provide shaping of theprojection f of reduced diameter and forming of a press-in holeMeanwhile, the stripper 45 presses the extended enlarged head 5a, toswage it into a chamber blocked by the outer punch 47 and the formingdie 36 that is the flange forming die hole 38 thereby to form the flangeb. In the upper portion thereof the head d is formed through enlargementof the diameter so as to correspond with the inner diameter of the outerpunch 47, and in the center hole 70 held its shape by the center punch44 is formed a blind bore e.

The center punch 44 in the third punch 43 of the final forging pressmachine C, may be provided with, instead of the stripper 45, aperipheral step of enlarged diameter which is equal to that of thestripper.

As stated with reference to the above preferred embodiment, the presentinvention relates to forming of'a terminal as shown in FIGS. 4 and 5from a cylindrical blank material 1 by means of cold forging method, inwhich there occurs no waste of material such as chip or the like whichwould inevitably arise in the prior cutting method. The presentinvention also allows forming of the terminal in a precise shape andhighly improves forming efficiency and hence enables the production costto be reduced remarkably.

We claim:

1. A cold forging method for producing a terminal comprising the stepsof:

feeding a cylindrical blank material into a swaging die and swaging saidcylindrical blank material with a first punch to form a firstintermediate product having an enlarged head portion with a shallowrecess therein and a center projection disposed respectively above andbelow a middle portion which has the original outer diameter of theblank material;

feeding the first intermediate product into a prepressing die and deeplydriving a second punch into the center of said recess in said enlargedhead to extrude the material backward increasing its axial lengththereby to form a second intermediate product having a deep center holewhich substantially corresponds in diameter with the outer diameter ofsaid second punch; and feeding the second intermediate product into aforming die so that the head projects from said forming die and strikingsaid head with a third punch comprising a center, a tubular and an outerpunch, said center punch being inserted into the center hole of thesecond intermediate product to maintain the inner peripheral shapethereof, said tubular punch striking the upper surface of the head toform, in cooperation with an inner periphery of the outer punch, aflange between the outer punch and a corresponding contact surface ofthe forming die and a plurality of detent projections on the bottomsurface of the flange.

2. A cold forging apparatus for producing a terminal which comprises; aswaging press machine including a swaging die having a first die holecomprised of a first portion of substantially the same diameter as thediameter of a cylindrical blank material, a second portion of enlargeddiameter formed above said first portion and connected therewith througha first tapered portion and a third portion of reduced diameter intowhich a first ejector is inserted and formed below and connected withsaid first portion; a first punch substantially corresponding indiameter with said second portion and having a small projectioncentrally provided thereunder, said first punch being adapted forswaging said cylindrical material in said swaging die to form anenlarged head portion having a shallow recess and a center projectionrespectively above and below a midde portion having the originalouterdiameter of the blank material; a pre-pressing forging machineincluding a pre-pressing die having a second die hole comprised of afirst section of substantially the same diameter as the diameter of saidmiddle portion and an axial length slightly longer than that of saidmiddle portion, a second section of an enlarged diameter substantiallycorresponding with the outer diameter of said enlarged head portionformed above and connected with said first section through a secondtapered portion and a third section of reduced diameter substantiallycorresponding with the diameter of said third portion and into which asecond ejector is inserted, said third section being formed below andconnected with said second section; a second punch substantiallycorresponding in diameter with the shallow recess and longer than saidrecess in axial length, said second punch being adapted for striking thefirst intermediate product and being driven deeply into said recess inthe enlarged head to extrude the material backward increasing its axiallength thereby to form a deep center hole; a final forging press machineincluding a forming die having a third die hole comprising a first partwhich is substantially equal in axial length to the length from thebottom of the intended middle portion of a finished product to the lowerend of the intended flange and in diameter to the original outerdiameter, a flange-forming second part of an enlarged diameter which isformed above said first part and opens to the upper surface of theforming die, a plurality of tapered grooves formed equiangularly in thebottom of said flange-forming second part, a third part of a reduceddiameter substantially corresponding with the diameter of the thirdportion and the third section and into which a third ejector having aconic projection thereon is inserted, said third part being formed belowand connected with said first part; a third punch consisting of a centerpunch ofa diameter corresponding with that of the second punch, atubular punch slidably fitted around said center punch and biased by aspring and an outer punch encircling said tubular punch and having aninner diameter correspending with the outer diameter of an intended headof the finished product, said center punch being adapted to be insertedinto the center hole of the second intermediate product to sustain theinner peripheral shape thereof, said tubular punch striking an uppersurface of the head to form a flange between the outer punch and acorresponding contact face of the forming die, a plurality of detentprojections on the bottom surface of the flange and a conical bore inthe bottom of the center projection thereby to finish a determined shapeof a terminal.

1. A cold forging method for producing a terminal comprising the stepsof: feeding a cylindrical blank material into a swaging die and swagingsaid cylindrical blank material with a first punch to form a firstintermediate product having an enlarged head portion with a shallowrecess therein and a center projection disposed respectively above andbelow a middle portion which has the original outer diameter of theblank material; feeding the first intermediate product into apre-pressing die and deeply driving a second punch into the center ofsaid recess in said enlarged head to extrude the material backwardincreasing its axial length thereby to form a second intermediateproduct having a deep center hole which substantially corresponds indiameter with the outer diameter of said second punch; and feeding thesecond intermediate product into a forming die so that the head projectsfrom said forming die and striking said head with a third punchcomprising a center, a tubular and an outer punch, said center punchbeing inserted into the center hole of the second intermediate productto maintain the inner peripheral shape thereof, said tubular punchstriking the upper surface of the head to form, in cooperation with aninner periphery of the outer punch, a flange between the outer punch anda corresponding contact surface of the forming die and a plurality ofdetent projections on the bottom surface of the flange.
 2. A coldforging apparatus for producing a terminal which comprises; a swagingpress machine including a swaging die having a first die hole comprisedof a first portion of substantially the same diameter as the diameter ofa cylindrical blank material, a second portion of enlarged diameterformed above said first portion and connected therewith through a firsttapered portion and a third portion of reduced diameter into which afirst ejector is inserted and formed below and connected with said firstportion; a first punch substantially corresponding in diameter with saidsecond portion and having a small projection centrally providedthereunder, said first punch being adapted for swaging said cylindricalmaterial in said swaging die to form an enlarged head portion having ashallow recess and a center projection respectively above and below amidde portion having the original outer diameter of the blank material;a pre-pressing forging machine including a pre-pressing die having asecond die hole comprised of a first section of substantially the samediameter as the diameter of said middle portion and an axial lengthslightly longer than that of said middle portion, a second section of anenlarged diameter substantially corresponding with the outer diameter ofsaid enlarged head portion formed above and connected with said firstsectiOn through a second tapered portion and a third section of reduceddiameter substantially corresponding with the diameter of said thirdportion and into which a second ejector is inserted, said third sectionbeing formed below and connected with said second section; a secondpunch substantially corresponding in diameter with the shallow recessand longer than said recess in axial length, said second punch beingadapted for striking the first intermediate product and being drivendeeply into said recess in the enlarged head to extrude the materialbackward increasing its axial length thereby to form a deep center hole;a final forging press machine including a forming die having a third diehole comprising a first part which is substantially equal in axiallength to the length from the bottom of the intended middle portion of afinished product to the lower end of the intended flange and in diameterto the original outer diameter, a flange-forming second part of anenlarged diameter which is formed above said first part and opens to theupper surface of the forming die, a plurality of tapered grooves formedequiangularly in the bottom of said flange-forming second part, a thirdpart of a reduced diameter substantially corresponding with the diameterof the third portion and the third section and into which a thirdejector having a conic projection thereon is inserted, said third partbeing formed below and connected with said first part; a third punchconsisting of a center punch of a diameter corresponding with that ofthe second punch, a tubular punch slidably fitted around said centerpunch and biased by a spring and an outer punch encircling said tubularpunch and having an inner diameter corresponding with the outer diameterof an intended head of the finished product, said center punch beingadapted to be inserted into the center hole of the second intermediateproduct to sustain the inner peripheral shape thereof, said tubularpunch striking an upper surface of the head to form a flange between theouter punch and a corresponding contact face of the forming die, aplurality of detent projections on the bottom surface of the flange anda conical bore in the bottom of the center projection thereby to finisha determined shape of a terminal.